Add Expresion and Attribute support in read/write params

[cerveada]

Since Spark Agent 0.6.3 Expressions and Attributes can be present in read and write operations.

This doesn't cause any issues, but UI doesn't show all available information and/or shows them as raw data.

[wajda]

This should be fixed on the server side. Moving the issue to the main Spline repo.

[wajda]

No, sorry. It's actually a UI issue. Moving it back to the UI repo :)

[wajda]

This is a limitation of the ngx-json-view - nested properties rendering isn't customizable. The UI app makes little assumption about operation properties structure. In this case the atttribute or expression reference is nested to the generic operation parameters that are rendered as a plain JSON.

{
    "properties": {
        "table" : {
            "output": [
                { EXPRESSION }
            ]
        }
    }
}

table.output[0] is a custom property of that specific Write operation, generated by certain version of Spark under certain conditions.
To render it as an expression we either need to expect that that particular property contains an expression metadata and use a separate widget for that, or we need to replace ngx-json-view component with a customizable renderer that would introspect the content of nested properties and render them accordingly to their detected type.

In either case it requires more efforts and because of low priority of the issue I'm moving it out of the scope of this release.